1. Field of the Invention
The present invention relates to an image pickup apparatus and a control unit therefor. More particularly, the invention relates to an image pickup apparatus, which is suitable for the production of movies or broadcast programs, that can output a first image signal and a second image having different frame rates together, for example, a variable frame rate image and a playback image. The invention also pertains to a control unit for the above type of image pickup apparatus.
2. Description of the Related Art
Conventionally, in film production, to achieve special video effects, filming is performed while changing the speed of filming with a film camera, that is, changing the number of frames per second. For example, when filming is performed faster than normal speed and when playback operation is performed at normal speed, slow-motion playback images can be obtained. With this technique, high speed operation, such as a scene in which droplets are falling onto a water surface, can be easily and meticulously observed. Conversely, when filming is performed slower than normal speed and when playback operation is performed at normal speed, fast-motion playback images can be obtained. With this technique, a sense of speed in, for example, battle scenes or car chase scenes, can be increased so that the scenes become more realistic and have a greater impact.
In television program production, imaging, editing, and transmission of programs is being digitized. Due to the development of digital technologies, the image quality is becoming higher and the cost of devices for producing programs is becoming lower, and digitization of film production is also improving.
Because of the digitization of television programs or film production, when imaging with an image pickup apparatus (video camera), the frame rate can be changed to easily obtain special video effects, for example, fast-motion playback operation or slow-motion playback operation. Such an image pickup apparatus is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2000-125210. When imaging at a frame rate lower than a predetermined frame rate by using this image pickup apparatus and when performing playback at the predetermined frame rate, fast-motion playback images can be easily obtained. In contrast, when imaging at a frame rate higher than a predetermined frame rate and when performing playback at the predetermined frame rate, slow-motion playback images can be easily obtained.
When recording an image signal generated by imaging a subject at a variable frame rate on a recording medium, such as a video tape or an optical disc, the operator checks whether a desired image has been recorded with an image pickup apparatus. In this case, an image signal DVr obtained by playing back the recording medium is supplied to the image pickup apparatus, and then, the image pickup apparatus is operated in synchronization with the image signal DVr. Then, the image based on the image signal DVr is displayed on an electronic viewfinder or a monitor connected to the image pickup apparatus.
When the frame rate of the image signal obtained by picking up a subject image (hereinafter such an image signal is sometimes referred to as an “imaging signal”) is different from that of the image signal DVr obtained by playing back the recording medium (hereinafter such an image signal is sometimes referred to as a “playback image signal”), the imaging signal cannot be generated or displayed since the image pickup apparatus is operated in synchronization with the playback image signal DVr while the recorded image is being checked. Accordingly, the image frame adjustment or focus adjustment cannot be performed in advance by displaying the variable frame rate image while checking the recorded image.